Hello,
The 500 server error could mean a few different things.
It would be difficult to determine the specific cause and solution from forums
What I would advise would be to contact us via ticket or an email to info@hostpapasupport.com
You can also contact us via phone or chat. 24 hours a day.
Also, I came across this link which helps explain 500 errors and common ways of troubleshooting them.
http://pcsupport.about.com/od/findbyerrormessage/a/500servererror.htm